Thomas main



(No Model.) 3 Smets-sheen `1. T. MAIN.

FURNAE POR STEAM GENERAVTRS.

`Patented Mar. 6,1888.

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"8 sheets-sheet 2'. T. MAIN. FUBINACE FOR STEAM GENERATRS.

(No ModeL)v Patented Mar.

(No Model.)

3 sheets-sheet 3'. vT. MAIN.V y FURNAGE lPOR STEAM GENBRATORS.

No. 378,967. .Patented Mar. 6,Y 1888.

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nire raras .Afrriwrl OFFICE.

THOMAS MAIN, OF JERSEY' CITY, NEW JERSEY.

FURNACE FOR STEAM-GENERATORS.

SPECIFICATION forming part of Letters Patent No. 378,967, dated March 6, 1888.

l Application filed May 18,1887. Serial No. 238,639. (No model.)

To all whom, it may concern.:

Be it known that I, THOMAS MAIN, of Jersey City, in the county of Hudson and State of New Jersey, have'invented a new and useful Improvement in Furnaces for Steam-Generators, of which the following is a specification.

My invention relates to those steam-generator furnaces in which a forced blast is supplied, either above or below the grate, or both above and below the grate, as may be best adapted to different stages in the combustion of fuel, and steam-generators embodying furnaces of this character are shown in my United States Letters Patent No. 352,142, dated November 9, 1886.

In carrying out my pres/ent invention there is employed, in connection with the steamgenerator furnace, an inner perforated liningplate above the grate, which forms a space between it and the front plate of the furnace, and inward of the front end of the furnace, an air-heater and a hot-air pipe leading from said heater and communicating with the front plate of the furnace by branches above and below the grate, and valves provided with stems leading forward through the branches and pipe and controlling openings through the front. These Vvalves may be ofthe rotary disk or register character, and their rotary stems, whichv extend forward through the branches and pipe, are provided on the front of the air-pipe with handles, whereby the valves may be operated.

So far as the invention is above described it applies both to steam-generators in which the furnace is beneath the shell of the generator proper and to generators in which the furnace or furnaces are formed within internal fines; but when the invention is applied to a steamgenerator having an internal tubular furnace the front plate closes the outer end of the furnace, and the perforated inner plate or lining above the grate forms within the outer end of the furnace an air-space.

The invention consists in novel combinations of parts, which are hereinabove briefiy referred to, and hereinafter pointed out in the claims.

In the accompanying drawings, Figure 1 is a longitudinal vertical section of a steamgenerator embodying my invention, and in which the furnace is beneath the cylindric shell respectively, a front elevation and longitudinal section of two sets of marine boilers to which my invention is applied. Fig. 7 is a front elevation, upon a larger scale, of the parts which are applied to the front of an internal tubular furnace. Fig. 8 is a vertical section on the dotted line c z, Fig. 7. Fig. 9 is a similar section upon the dotted line 's s, Fig. 7; and Fig. 10 is a horizontal section upon the plane indicated by the dotted line o o, Fig. 7.

Similar letters of reference designate corresponding parts in all the figures.

Referring first to Figures 1, 2, 3, 4, and 4*, A designates the cylindric shell of a steamgenerator, which is arranged within a casing composed of a metallic shell, B, and brickwork or other refractory material, B. The furnace C in this generator is below the cylindric shell and is provided with the usual grate, c, below which is the. ash-pit C', and from the furnace C the products of combustion pass beneath the generator to the back connection, CZ, thence forward through the tubes c to the front connection, C3, thence upward through a heater, which is in the smoke pipe or stack C. As here represented, the heater consists of vertical tubes c2,which have their upper and lower endsinserted in suitable horizontal plates or diaphragms, c3 ci. The course taken by the products of combustion is indicated by the arrows in Fig. 1, and in the smoke-stack C'L is a damper, c5, whereby the rapidity cf draft may be controlled. The heater which is in the smoke-pipe is supplied with air through a suitable pipe, d, from a pressure-blower, D, which is shown in Figs. 4 and 4*. This pressure-blower may be of the Root or other type, and, as here represented, it is driven by a compound balanced engine, D, which may be constructed like that shown and described in my former patent, with the auger-handle crankshaft d coupled direct to the main shaft of the IOO blower and with two cylinders, d2 da, arranged at an angle of about twenty degrees, one rela- .tively to the other. By this arrangement of the cylinders, and by the use of the augerhandled crankshaft d/,the engine may be made very compact,and the pressure upon the crankshaft bearings and also the pressure in opposite direction upon the pistons workin g within the cylinders d2 d3 are very nearly balanced. From the air-heater a strong blast of heated air passes downward through a pipe, DE, here shown as extending through the front connection, C, upon the front of the furnace, and which is provided with branches d4 d5.

b designates the front plate of the furnace, in which is the door b, and the front plate of the furnace is provided around the door with a suitable perforated lining-plate, b2, as is best shown in Fig. 2, thereby forming within the front end of the furnace an airspace, S. rlhe door b may be likewise provided with a perforated inner plate or lining, b, and with an ordinary air-register, b4, for admitting the outside atmosphere. The branches d4 d5 from the pipe Dlz communicate, one with the air-space S above the grate c and the other with the ash-pit C', as is best shown in Fig. 3; and in the front of the furnace b are openings which are controlled by valves d di, here represented as of the rotary or disk-like form, or made in the form of rotary registers and controlled by stems da, which extend forward through the branches d* d5, and are provided forward of the pipe D2 with handles d, whereby the stems and valves may be turned. By means of these valves the admission of air may be controlled and in the different stages of combustion of the fuel placed in the furnace C the air may be admitted above the grate, below the grate, or in part both above and below the grate, as may be desired.

In the construction shown in Figs. 5 and 6 two sets of boilers-such as are suitable for a marine Steamshipare designated by the letter A', and each boiler or steam-generator is constructed with three furnaces, C, as best shown in Fig. 5, and C3 designates the connection through which the products of combustion escape upward through the tubes c'l of the heater and then to the smokestack 0*. d designates the inlet-pipe for air under pressure from the blower, and DL designates the pipe through which heated air under pressure passes downward to the generators. The pipe D2 is bifurcated near its lower end, and portions, each designated by the letter D2, lead downward on the front ofthe generator to cach furnace C, and communicate with each furnace by branches d1 di above and below the grate.

In Figs. 7, 8, 9, and l0 I have represented the construction of parts whereby the air-space S is formed in the front end portion of each of the tubular furnace-fines C, and also the construction of the valves and pipes, whereby air under pressure is admitted to the airspace S. A front plate,b, which may be of octagonal form, as represented in Fig. 7, laps slightly upon the front of the furnace, and is secured by bolts or rivets thereto. Above the grate c an inner lining or plate, b2, is provided, which is perforated throughout around the door b', and forms, in connection with the front plate, b, an air-space, S. rlhe door b'may likewisehave an inner perforated lining or air-distributer, b3, and may have an air-register, bi, for admitting atmospheric air tothe furnace. The pipe D2 is provided with branches d* d'5, which enter the front of the furnace, and which are secured to the front plate, l1, and by means of suitable register or disk-like valves, d di, the

air supplied from these branches d* d5 to the l air-space S, above the grate, and to the ashpit C is controlled. rlhe stems d for these valves extend forward through the branches dlx d5, and are provided in front of the pipe D2 with handles d, whereby they and the valves d di, with which they are connected, may be turned. It will therefore be seen that to apply my invention to an ordinary marine boiler having internal furnaces, whether it be a singie-ended boiler, as represented in Fig. 6, or double-ended boiler, such as is well known, it is only necessary to provide the front plate, b, and the perforated lining or inner plate, b2, and to connect therewith the air-pipe D, with its branches and valves.

I am aware that many plans have been devised for supplying heated air above and below the grate of a furnace, and hence l do not desire to broadly claim any such device, but limit my claim to the features of construction above described. It is very advantageous to have the hot-air space S inward of the end of the furnace, because then the front b is flush with the front end of the furnace and the re-4 maining portion of the generator front is wholly exposed, and it is very advantageous to have the airpipes D2 lead down on the front and have their branches communicate directly with the front plate, I), and to have the valves in the branches d4 d5, and to employ plain disk-valves with their stems extending forward through the branches.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The combination, with the front of a steam-generator furnace and a perforated lining-plate above the grate, forming a space between it and the front and having its depth inward of the front, of an air-heater and a hotair pipe leading from said heater and communicating by branches with the front of said space above and below the grate, and valves provided with stems leading forward through said branches and pipes and controlling openings through the front, substantially as herein described.

2. The combination, with the furnace-front b of a steam-generator furnace and the inner perforated lining, b2, above the grate, of a heater, the hot-air pipe and branches d* d5, communicating with the front b, the rotary dislr or register valves d (i7, controlling the openings in the front, and their operating- IOO IIO

stems da, leading outward through said branches and provided on the front of the air-ppe with handles, substantially as herein described.

3. The combination, with aninternal tubu- 5 lar stealngenerator furnace and a front plate closing the outer end of the furnace, of a perforated inner plate or lining above the grate,

forming within the furnace and inward of the front thereof an air-Space, an airhcater and a Io hot-air pipe leading therefrom and provided with branches communicating with the front plate above and below the grate, and valves controlling the communication ofsaid branches with the said airspace and with the furnace below the grate, substantially as herein de- 15 scribed.

. THOMAS MAIN. Vitnesses:

G. HALL, FREDK.` HAYNES. 

